<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>计算器</title>
</head>
<body>
    <div id="app">
        <div class="input_num">
            <button @click="sub">-</button>
            <span>{{num}}</span>
            <button @click="add">+</button>
        </div>
    </div>
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <script>
        var app = new Vue({
            el:"#app",
            data:{
                num:1
            },
            methods:{
                sub:function(){
                    if(this.num > 0){
                        this.num --;
                    }else{
                        alert("最小为0，不能再减！")
                    }
                
                },
                add:function(){
                    if(this.num < 10){
                        this.num ++;
                    }else{
                        alert("最大为10，不能再加！")
                    }
                }
            }
        })
    </script>
</body>
</html>